The present invention provides thermoplastic polymer mixtures containing at least one mould release agent with a polyol component consisting of a parent substance with 4 or more carbon atoms, 3 or more hydroxyl groups, more than one hydroxyl group esterified with aliphatic C1-C32 carboxylic acids and one or more than one free hydroxyl group, the use of such polyol components as mould release agents for thermoplastic polymer mixtures and moulded items made from these thermoplastic polymer mixtures.
When processing thermoplastic polymer mixtures, the production of moulded parts some of which have extremely complicated spatial shapes is a main application. Mould release agents are added to the polymer mixture itself or placed in the machines during processing in order to ensure, or simplify still further, removal of the moulded parts from the mould. In addition, these are intended to improve the surface quality.
The disadvantage of this procedure is contamination of the product with additives which can have a detrimental effect on the moulded item during preparation, storage or use.
Esters of long chain fatty acids with hydroxy components, in particular glycerine, have proven useful in the prior art.
DE-OS-20 64 095 describes the addition to polycarbonates of fatty acid esters of trihydric alcohols as mould release agents.
DE-OS-25 07 748 describes the improvement in the mould release characteristics of polycarbonates due to the addition of polyalcohols completely esterified with fatty acids.
DE-OS 27 01 725 describes the addition of part-esters of specific alcohols to polycarbonates for the purpose of mould release.
JP-A-45-24 439 describes the addition to polycarbonates of part-esters in amounts of 0.05 to 5% for the purpose of mould release.
JP-A-72-45 934 describes antistatic-modified polycarbonates with 0.1 to 5 wt. % of fatty acid monoglycerides.
JP-A-60-81 245 describes the addition of part-esters to low-chlorine polycarbonates in order to prevent corrosion of the moulds.
JP-A-2-225 558 describes polycarbonate sheets which contain part-esters of polyols and aliphatic monocarboxylic acids.
Japanese patent application 90-12-510 describes substrates for CDs which consist of polycarbonate and contain 0.002 to 5% of fatty acid monoglycerides.
Japanese patent application 90-294 979 describes polycarbonates for optical discs which contain 0.06 to 0.09% of glycerine monostearate.
U.S. Pat. No. 4,131,575 describes the addition to polycarbonates of full esters of polyhydric alcohols or monoesters of polyhydric alcohols, to improve mould release.
U.S. Pat. No. 4,743,641 describes the addition of glycerine monostearate, diglyceride monostearate, glycerine monopalmitate or sorbitane monostearate to polycarbonates.
EP-A-205 192 describes polycarbonate mixtures to which has been added esters of glycerine and of pentaerythritol. Glycerine monostearate is preferred in that document.
EP-A-213 413 describes the addition of part-esters to polycarbonates for optical purposes.
EP-A-417 775 describes moulded items for optics made of polycarbonates which contain fatty acid monoglycerides.
EP-A-511 640 also describes the addition of part-esters to polycarbonates for optical purposes.
EP-A-732 360 describes polycarbonate mixtures with mixtures of glycerine monostearate and glycerine tristearate.
The mould release agents in the prior art, such as for example the frequently used glycerine monostearate, have the disadvantage that they can lead to reactions with the polycarbonate. This impairs the thermal and oxidative resistance of the materials which may be expressed, for example, by yellowing. This is undesirable, in particular for optical applications of polycarbonate. This applies in particular to processing processes which involve high thermal stress for the material or for applications which require special optical quality. The mechanical properties of the polymer may also be modified undesirably as a result of these reactions. In addition coatings may appear on parts of the machines.
In the case of fully esterified alcohol components, the mould release characteristics are inadequate.
There is therefore a constant demand for novel mould release agents for thermoplastic polymers such as, for example, polycarbonate and/or polycarbonate blends.
The object therefore consists of developing a mould release agent for polycarbonates which has a very low, or even zero, tendency to react under the conditions of preparation and processing, especially during the preparation of products for optical applications such as compact discs and digital versatile discs (DVDs), have a good mould release effect and thus lead to improved quality and higher data security in the case of optical applications. This is achieved by polymer mixtures according to the invention.
Accordingly, the present application provides thermoplastic polymer mixtures containing at least one polycarbonate and at least one mould release agent with at least one polyol component wherein at least one polyol component (I) consists of a parent substance with 4 or more carbon atoms, 3 or more, preferably 4 or more, hydroxyl groups, more than one hydroxyl group esterified with aliphatic carboxylic acids and one or preferably more than one free hydroxyl group.